Heating unit



Oct. 18, 1960 L. c. HANsoN HEATING UNIT Filed neo. e, 195e V12 CQNToR.

@7' Y gg 62726022* Ml )G01 f @n r r r United States Patent C HEATING UNIT Leroy C. Hanson, Elmhurst, Ill., assiguorto Ferro Corporation, a corporation of h10 Filed Dec. 8, 1958, Ser. No. 778,668

6 Claims. ('Cl. 219-37) This invention relates to a heating unit and more particularly to a heating unit particularly adapted for use with electric stoves and the like.

It is a general object of the present invention to produce a new and improved heating unit of the character described.

It is a more particular object of the invention to produce a heating unit particularly adapted to form a part of an electric stove in which the heating unit is in the form of a coil supported in position on the stove in a manner permitting unrestrained movement between the coil and its support due to thermal expansion and contraction of the unit.

ln the design and manufacture of heating units for electric stoves, it has been customary to provide the unit in the form of a coil which is supported over a spillage pan by means of an element often taking the general form of a spider, that is, an element provided with legs extending generally radially from approximately the center of the coil outwardly to its edges. The primary purpose of the support or spider is to sustain the weight of pots and pans placed on the heating coil. In such constructions it is the normal practice to secure the coil to the spider in various manners such as, for example, by providing notches in the legs of the spider into which the coil nests or otherwise to provide positive attachment between the convolutions of the coil and the legs of the support as by welding, the use of clips, or the like.

The changes in shape or size which the coil undergoes as a result of thermal contraction and expansion during use has created a number of problems inasmuch as all methods which employ a positive attachment between the coil and its support causes stresses to be set up in the two elements leading to distortion of the coil or support, and sometimes to breakage of the attaching device.

In conjunction with the problem of providing a support for the coil together with a means of accurately position ing the coil in proper place, is the problem of permitting easy withdrawal of movement of the heating unit from its normal cooking position so that the spillage pan normally found beneath the coil may periodically be cleaned.

In accordance with the present invention, however, there is provided a heating coil which, while supported by a spider of more or less conventional construction, is wholly unrestrained in its movements caused by ternperature changes and which may easily be removed to permit cleaning of the adjacent areas.

Thus, it is a primary feature of the present invention to provide a heating unit in the form of a coil which is free to change shape with the changes in its temperature, which is fully supported to provide a iirm surface for pots and the like, and yet which is so designed as to be simply and easily moved from its position so as to give clear access to adjacent areas for cleaning.

Other and further features and advantages will be readily apparent from the following description and drawings in which:

2,957,068 Patented Oct. 18, 1960 Fig. 1 is a top plan view of a heating unit embodying the invention;

Fig. 2 is a vertical section along line 2-2 of Fig. 1; and

Fig. 3 is an enlarged vertical section along line 3--3 Of Fig. l.

While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and will herein be described in detail one specific embodiment, with the understanding that the present disclosure is to be considered as an exemplitication of the principles of the invention and is not intended to limit the invention to the embodiment illustrated. The scope of the invention will be pointed out in the appended claims.

Referring now to the drawings, there is shown a heaty ing unit 10 embodying the features of the invention previously discussed, including a base generally designated 11, the base forming a spillage pan 12 having a lip 13 overlying and supported by a stove surface 14. A ring 15 forms the outer boundary of the heating unit and is curved downwardly to meet with the surface 14. For heat insulation purposes the pan may be provided with a double bottom 16 spaced from the bottom of the pan itself.

A pair of terminal blocks 17 is secured to the outer side of the pan 12 at diametrically opposite portions thereof and each of the terminal blocks is provided with a snap-in contact 18. The contacts comprise ribbons 19 of conducting metal possessing spring-like resiliency, each having a U-shaped receiving portion 20 to receive the Contact ends 21 of a heating coil generally designated 22. The heating coil is, as illustrated, formed with a coil portion 23 and two oppositely extending terminal portions 24 which carry the contacts 21.

Underlying and supporting the heating coil 22 is a support or spider 25 having outwardly extending legs 26 underlying and carrying the coil. Secured to each terminal portion of the heating unit are fingers 27, with the fingers in turn being secured to the outer end of the adjacent spider leg 26. Like the legs 26 of the spider, the fingers 27 are made of metal strips having a thickness which is but a fraction of their width. Each finger 27 is provided with a lift tab 28 for purposes hereinafter to be described.

The spider 25 is unsecured to the pan 12 and is positioned merely by inwardly struck portions 29 formed in the side walls of the pan 12 with the outer ends of the legs 26 of the spider being provided with a finger-like extension 30 overlying the portions 29.

As previously indicated, contacts 18 are of the snapin type. Thus, when it is desired to move the coil from the position shown (for the purpose of cleaning the spillage pan or otherwise), it is merely necessary to exert an upward force on the lift tab 28 thereby snapping the contacts 21 out of their mating contacts on the terminal block, and thereby removing the spider and coil from the spillage pan. It will be noted that the only positive connection between the heating coil 22 and the spider 25 is at the terminal portions 24 rather than at any point in the actual coil portion 23, and that the lingers 27 providing such attachment serve the dual purpose of securing means as well as facilitating removal of the heating coil and spider as a unit. Thus it will be clear that during use the coil portion is adequately and firmly supported by the spider 25 and yet is unrestrained in its thermal movements relative thereto. In addition, the removal and replacement of the coil and spider are simply and easily achieved so that ready access may be had to the area of the unit normally beneath the coil.

Thus, there has been provided a heating unit possessing the desired features of easy removability particularly of the coil and spider as a unit, without including as a portion of such construction attaching means securing the coil portion andspider of the unit together, thus leaving the coil substantially unrestrained.

I claim: Y

1. A heating unit comprising a base, a coil support removably carried on the base, a heating coil having a coil portion carried by the support and having terminal portions, means securing only the terminal portions to the support whereby the coil portion is free to move relative to the support with thermal expansion and contraction, and contacts carried on said base for connection with said terminal portions of the coil.

2. A heating unit comprising a base, a coil support removably car-ried on the base, a heating coil having a coil portion carried by the support and having substantially diametrically opposite terminal portions, means securing only the terminal portions to the support whereby the coil portion is free to move relative to the support with thermal expansion and contraction and contacts carried on said base for connection with said terminal portions of the coil.

3. A heating unit comprising a base, a coil support removably carried on the base in the form of a spider having generally outwardly extending legs, a heating coil having a coil portion carried by the spider and having terminal portions, means securing only the terminal portions to the outer ends of the legs of the spider whereby the coil portion is free to move relative to the support with thermal expansion and contraction and contacts carried on said baseV for connection with said terminal portions of the coil.

4. A heating unit comprising a base including a spillage pan, a coil support in the form of a spider having outwardly extending legs resting in the pan but unsecured thereto, a heating coil having a coil portion carried by the spider and having substantially diametrically opposite terminal portions, and a pair of snap-in-snap-out contacts secured to the base and positioned to receive said terminal portions, said coil portion being unattached to said spider whereby said coil portion is free to move thereover with thermal expansion and contraction.

5. A heating unit comprising a base including a spillage pan, a coil support in the form of a spider having outwardly extending legs resting in the pan but unsecured thereto, a heating coil having a coil portion carried by the spider and having substantially diametrically opposite terminal portions, a pair of snap-in-snap-out contacts secured to the base and positioned to receive said terminal portions, and means securing only the terminal portions to the outer ends of said legs whereby the coil portion is free to move thereover with thermal expansion and contraction.

6. A heating unit comprising ra base including a spillage pan, a coil support in the form of a spider having outwardly extending legs resting in the pan but unsecured thereto, a heating coil having a coil portion carried by the spider and having substantially diametrically opposite terminal portions, a pair of snap-in-snap-out contacts secured to the base and positioned to receive said terminal portions, and a pair of fingers each secured at one end to the terminal portions of the coil and at the other end to the outer ends of .the adjacent leg of the spider, each of said fingers being provided with lift tabs and said ngers constituting the only positive connection between the heating coil and the spider whereby the coil is free to move over the spider with thermal expansion and contraction.

References Cited in the le of this patent UNITED STATES PATENTS 1,837,975 M'allett Dec. 22, 1931 2,368,051 Tuttle Ian. 23, 1945 2,455,186 McCormick Nov. 30, 1948 

